The zebrafish retina has dedicated stem cells that permit continued addition of photoreceptors and neurons throughout life, and are capable of bringing about remarkable regeneration following damage to the retina. The retinas of humans and other mammals do not have such ongoing growth or regenerative capacity, though latent stem cells may reside in our retinas. This project seeks to study the factors that control the establishment of the retinal stem cells in the zebrafish and their fate decisions to proliferate or differentiate. My preliminary studies have identified that certain members of the canonical Wnt cascade play a role in controlling the size of the stem cell niche, the number of stem cells, and the decision for the stem cells to proliferate or differentiate. I hypothesize that this pathway, which has been identified in control of stem cell fate in other epithelial structures such as intestine and epidermis, may be a key pathway for the control of initial retinal development, the ongoing addition of retina at the retinal periphery, and regeneration following damage. Further investigation of the role of this pathway in the control of stem cell number during development and regeneration of the fish retina should set the stage for future work to stimulate.the normally latent stem cells in the mammalian eye. Such work could lead to therapeutic treatments for degenerative retinal diseases including retinitis pigmentosa and macular degeneration. [unreadable] [unreadable]